System and Method for Monitoring Ablation Size

1. A method for monitoring tissue undergoing ablation, the method comprising: transmitting microwave energy from a power source to a microwave antenna to form a tissue ablation zone; monitoring reflected power associated with the microwave antenna to generate a reflected power signal; calculating a derivative indicative of rise and fall portions of the reflected power signal, wherein when the derivative is taken during a rise portion of the reflected power signal the measured reflected power is assigned a positive value and when the derivative is taken during a fall portion of the reflected power signal the measured reflected power is assigned a negative value, the positive and negative values of the reflected power signal indicating when the microwave antenna and tissue in a near field of the ablation zone are approaching a respective steady-state condition or an impedance match between the microwave antenna and tissue in the near field; communicating a control signal to the power source when a predetermined reflected power is reached at the microwave antenna; and adjusting the amount of microwave energy from the power source to the microwave antenna.

2. The method according to claim 1 , further comprising: accessing at least one data look-up table including data pertaining to a control curve varying over time and being representative of at least one electrical parameter associated with the microwave antenna; and generating a signal when a predetermined threshold value of the at least one electrical parameter is corresponding to the radius of the ablation zone.

3. The method according to claim 2 , wherein the at least one electrical parameter is selected from the group consisting of impedance, power, voltage and current.

4. The method according to claim 3 , further comprising correlating a reflected signal generated by the power source associated with the microwave antenna during transmission of microwave energy to the microwave antenna when the microwave antenna is in a near field state with the tissue ablation zone.